1. Field of the Invention
This invention relates to a tone arm bearing system.
2. Discussion of the Prior Art
Conventionally, tone arm bearing systems include ball bearings. In the prior art system of FIG. 1, 1 is a tone arm, 2 is a bracket, 3 is a rotatable shaft, 4 is a stop and 5 is a fixed bushing. In order to insert balls 6 and 6' at the top and bottom opening edges, recess 7 and 7' are formed. 8 is a clamping nut for shaft 3, 9 is a washer, 10 is an arm base and 11 is a cabinet. The shape of the above recess 7 and 7' is sometimes stepped as shown in FIGS. 1 and 2A and other times, they are tapered as shown in FIG. 2B.
In the case of FIG. 2A, a space l for mechanical precision is formed between ball 6 and recess 7 and a space l' for adjustment to obtain arm sensitivity is formed between ball 6' and recess 7'. Even in the FIG. 2B type, a space l' for adjustment is formed.
The above-mentioned spaces l and l' are in fact considered important elements in deciding the quality of the arm since shaking due to these spaces l and l' seriously affect the tone quality. In other words, due to the vibration added to the arm by external sound pressure and vibration received from the player cabinet, the fulcrum of the arm is not fixed and complex shaking occurs in both the vertical and horizontal directions.
Consequently, in the case of conventional bearing systems, the fulcrum of the arm moves in a complex pattern while the arm traces the record surface and shortcomings such as (a) high frequency distortion and tracing distortion result, especially near the arm resonance region, (b) needle jumping readily occurs and (c) the howling characteristic deteriorates.